The field of the present invention is product discrimination systems using remote sensing.
Fruit and vegetable products have been subject to sorting based on color in the past. Initially, such tasks were performed manually. More recently, as labor continues to be more and more expensive and unavailable, machine sorting by color has been attempted. A device capable of sorting by color is described in U.S. Pat. No. 4,106,628 to Warkentin et al., the disclosure of which is incorporated herein by reference. In this system, color from a product unit is directed through lenses, fiber optics and filters to a sensing mechanism. In the actual system, light from both sides of a product unit was gathered in a single scan per product unit by two bundles of optic fibers looking from opposite sides of the product unit. Each optic fiber bundle was split and combined with a respective split portion of the other bundle. Therefore, each resulting optic fiber bundle had light from both sides of the product unit. Filters of different wavelength capacity were employed to filter the light derived from the resulting two fiber optic bundles. Red and green filters were given as examples, one filter for each resulting bundle. The signals generated by the filtered light were then compared with a standard such that a red/green color classification could have been made based on the readings compared with the standard.
More complicated sensing devices have been developed which use line scan cameras for determining such attributes as cross-sectional area. Such cameras have used light to present pixel information which may then be processes for summation and the like. For example, cross-sectional area may be determined by counting the number of pixels registering presence of the product unit. In order to detect color using such a system, a central processing unit having substantial capacity would be required because of the significant amount of data to be received and processed. With product units travelling at any reasonable speed past such a discrimination system, it quickly becomes impossible to keep up with the processing of relevant information without a very substantial data processing system. Further, being constrained to pixel units does not afford adequate latitude in controlling sensitivity.
To overcome the excessive amount of data, optical scanning of products using a variety of light spectra both in and beyond the visible spectrum has been attempted with the magnitudes of the sensed light spectra analyzed to determine physical attributes without requiring the analysis and handling of individual pixels.
In such a system, a focused image of a product unit is directed to a fiber optic array. The array has a first end which is arranged in a rectangle. Because of this arrangement, the fiber optic cable receives what approximates a line scan image. The image is averaged and then divided and directed through filters to provide a plurality of sensed signals for different wavelengths. Intensity may be measured for each selected wavelength spectrum. Consequently, only a few signals, the magnitude of each separately filtered portion of the image, need be processed. FIGS. 1 through 6 illustrate such a prior sensing system. FIGS. 2 through 6 further illustrate hardware incorporated into the preferred embodiment herein. Reference is also made to European Patent Application Publication No. 0 346 045 to Richert, the disclosure of which is incorporated herein by reference.
Devices for handling the product units have also been developed. Such processing devices generally include conveyors passing work stations where workers were able to distinguish and separate product units. With the advent of electronics and sophisticated software, conveying systems have required more exacting placement of the product units, separation of those units, proper orientation and reorientation and means for quickly but gently separating the units from the system. The demands for such exacting placement, control and operation are orders of magnitude more stringent than for manual processing.
An early system for handling of products in a manner acceptable for automatic sorting is disclosed in U.S. Pat. No. 4,106,628 to Warkentin et al. In this system, a conveyor was employed which included elements capable of tipping to off-load individual units of a product being processed. The nature of the conveyor permitted some variety in shapes and sizes, including elongated products. However, a range of round or oval products in smaller sizes was not as easily accommodated.
Further off-loading conveyor systems have been developed for handling a wide variety of product including small spherical and ovular shapes and easily damaged units. Product could also be viewed from two sides through the off-loading of product from one conveyor onto another. Reference is made to British Patent 2 143 491 to Warkentin, the disclosure of which is incorporated herein by reference. Bow tie rollers have been mounted to a chain conveyor to define concavities between adjacent rollers. Off-loading elements or paddles have been arranged between rollers to face the concavities. They may be actuated to void the concavity by sweeping therethrough. FIGS. 7 through 15 illustrate such a prior conveying system. These same mechanisms are contemplated for use in the preferred embodiment of the present system. Reference is also made to European Patent Application Publication No. 0 345 036 to Warkentin, the disclosure of which is incorporated herein by reference.